using GostCryptography.Properties;
using System;

namespace GostCryptography.Asn1.Ber
{
    [Serializable]
    public class Asn1ObjectIdentifier : Asn1Type
    {
        public static readonly Asn1Tag Tag = new Asn1Tag(0, 0, ObjectIdentifierTypeCode);

        [NonSerialized]
        protected OidValue OidValue;

        public OidValue Oid => OidValue;


        public Asn1ObjectIdentifier()
        {
            OidValue = null;
        }

        public Asn1ObjectIdentifier(OidValue oidValue)
        {
            OidValue = oidValue;
        }

        public static Asn1ObjectIdentifier FromString(string value)
        {
            return string.IsNullOrEmpty(value) ? null : new Asn1ObjectIdentifier(OidValue.FromString(value));
        }

        public override void Decode(Asn1BerDecodeBuffer buffer, bool explicitTagging, int implicitLength)
        {
            var len = explicitTagging ? MatchTag(buffer, Tag) : implicitLength;

            if (len <= 0)
            {
                throw ExceptionUtility.CryptographicException(Resources.Asn1InvalidLengthException);
            }

            OidValue = OidValue.FromArray(buffer.DecodeOidContents(len));
            buffer.TypeCode = ObjectIdentifierTypeCode;
        }

        public override int Encode(Asn1BerEncodeBuffer buffer, bool explicitTagging)
        {
            if (((OidValue.Items.Length < 2) || (OidValue.Items[0] > 2)) || ((OidValue.Items[0] != 2) && (OidValue.Items[1] > 0x27)))
            {
                throw ExceptionUtility.CryptographicException(Resources.Asn1InvalidObjectIdException);
            }

            var len = 0;

            for (var i = OidValue.Items.Length - 1; i >= 1; i--)
            {
                len += buffer.EncodeIdentifier((i == 1) ? ((OidValue.Items[0] * 40) + OidValue.Items[1]) : OidValue.Items[i]);
            }

            if (explicitTagging)
            {
                len += buffer.EncodeTagAndLength(Tag, len);
            }

            return len;
        }

        public override void Encode(Asn1BerOutputStream outs, bool explicitTagging)
        {
            if (((OidValue.Items.Length < 2) || (OidValue.Items[0] > 2)) || ((OidValue.Items[0] != 2) && (OidValue.Items[1] > 0x27)))
            {
                throw ExceptionUtility.CryptographicException(Resources.Asn1InvalidObjectIdException);
            }

            var len = 1;

            for (var i = 2; i < OidValue.Items.Length; i++)
            {
                len += Asn1RunTime.GetIdentBytesCount(OidValue.Items[i]);
            }

            if (explicitTagging)
            {
                outs.EncodeTag(Tag);
            }

            outs.EncodeLength(len);
            var ident = (OidValue.Items[0] * 40) + OidValue.Items[1];
            outs.EncodeIdentifier(ident);

            for (var i = 2; i < OidValue.Items.Length; i++)
            {
                outs.EncodeIdentifier(OidValue.Items[i]);
            }
        }

        public override bool Equals(object obj)
        {
            if (this == obj)
            {
                return true;
            }

            if (!(obj is Asn1ObjectIdentifier))
            {
                return false;
            }

            var other = (Asn1ObjectIdentifier)obj;

            if (OidValue == other.OidValue)
            {
                return true;
            }

            if (OidValue == null || other.OidValue == null)
            {
                return false;
            }

            return OidValue.Equals(other.OidValue);
        }

        public override int GetHashCode()
        {
            return OidValue?.GetHashCode() ?? base.GetHashCode();
        }

        public override string ToString()
        {
            return OidValue?.ToString() ?? base.ToString();
        }
    }
}